(1) Field of the Invention
The present invention relates to a color liquid crystal display device and more particularly to a color liquid crystal display device generally called an in-plane field type.
(2) Description of the Prior Art
The color liquid crystal display device, generally called in-plane field type, has two transparent substrates arranged opposite each other with a liquid crystal layer interposed therebetween and also includes pixel electrodes, or display electrodes, and counter electrodes, or common electrodes arranged on the liquid crystal layer side of at least one of the two transparent substrates at locations corresponding to each unit picture element or pixel. In this construction, the color liquid crystal display device changes a light transmissivity or transmittance of the liquid crystal layer by an electric filed applied between the pixel electrode and the counter electrode whose component is almost parallel to the transparent substrate surfaces.
Such a color liquid crystal display device has come to be known for a wide viewing angle characteristics, a capability that enables a viewer to recognize images clearly even when he or she looks at the display surface from a wide viewing angle.
In a liquid crystal display device using the active matrix system, the unit pixels are respectively provided with switching elements. A counter voltage, which is a constant voltage or an AC voltage, is applied to the counter electrodes through a counter signal line common to a group of unit pixels arranged in a row direction. The pixel electrodes receive a video signal, which comes from a video signal line, common to a group of unit pixels arranged in a column direction, through the switching elements that are turned on by a scan signal from a scan signal line common to the row of unit pixels.
In this case, the scan signal lines, the video signal lines and the counter signal lines are all formed virtually linear and three adjoining unit pixels of a group arranged in the row direction (the direction in which the scan signal line extends) are assigned with three primary colors respectively.
That is, there adjoining unit pixels are regarded as a single unit pixel for color display.
Features of the in-plane field type liquid crystal display device have been disclosed in, for example, Japanese Application Publication No. Hei 5-505247 (PCT/WO91/10936), and Japanese Patent Publication No. 21907/1988 (JP-B-63-21907).